As a 1-gram sample of H2O(1) changes to H2O(g)
at 100°C, the potential energy of the molecules
A. decreases
B.
increases
C. remains the same

Option B

Explanation:

Changing of a substance from liquid to a gas, is known as vaporization. During vaporization a substance absorbs thermal energy. The forces between particle is very weak and hence they gain potential energy. Thus, while changing from liquid to gas, energy gets absorbed to increase the potential energy. This energy is known as latent heat of vaporization.

Hence, option B is correct

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.